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shell/platform/android/io/flutter/embedding/android/FlutterActivity.java

@@ -505,6 +505,16 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
     configureStatusBarForFullscreenFlutterExperience();
   }
 
+  /**
+   * Registers the callback with OnBackInvokedDispatcher to capture back navigation
+   * gestures and pass them to the framework.
+   *
+   * This replaces the deprecated onBackPressed method override in order to support
+   * API 33's predictive back navigation feature.
+   *
+   * The callback must be unregistered in order to prevent unpredictable behavior
+   * once outside the Flutter app.
+   */
   @VisibleForTesting
   public void registerOnBackInvokedCallback() {
     if (Build.VERSION.SDK_INT >= 33) {
@@ -514,6 +524,12 @@ public void registerOnBackInvokedCallback() {
     }
   }
 
+  /**
+   * Unregisters the callback from OnBackInvokedDispatcher.
+   *
+   * This should be called when the activity is no longer in use to prevent unpredictable
+   * behavior such as being stuck and unable to press back.
+   */
   @VisibleForTesting
   public void unregisterOnBackInvokedCallback() {
     if (Build.VERSION.SDK_INT >= 33) {